JP2013501564A - Non-magnetic high-voltage charging system used for cardiac stimulators - Google Patents

Abstract

  The cardiac defibrillator stores electrical wires or terminals 24 connected to or configured to be connected to a defibrillation electrode pad, a storage element 52 and a voltage effective to supply a cardiac defibrillation shock. And an electric circuit 32, 32a, 32b having a piezoelectric transformer 50 configured to charge the element. The electrical circuit is configured to discharge the storage element through the electrical wire or terminal to deliver a cardiac defibrillation shock to the electrical wire or terminal.

Description

  The present invention relates to medical technology, magnetic resonance technology, and related technology.

Magnetic resonance (MR) is a useful technique for performing medical diagnoses such as MR imaging and MR spectroscopy. These techniques generally use MR scanners with a main magnet that produces a static magnetic field in the range of 0.1-7.0 Tesla, although higher or lower magnetic fields can be used. The main magnet is generally an electromagnet using resistive or superconducting windings and can have various structures, such as a solenoid structure, an open bore vertical structure, and the like. The other electromagnet is configured to operate as a magnetic field gradient coil to selectively superimpose the magnetic field gradient on a static (B ₀ ) magnetic field. An optional shim coil imposes a shim magnetic field on a static (B ₀ ) magnetic field. The radio frequency subsystem (i) generates a radio frequency electromagnetic field at a magnetic resonance frequency to excite magnetic resonance in the subject, and (ii) receives a magnetic resonance signal from the subject in response to the excitation. Configured. Various pulse sequences generate magnetic resonance, spatially limit, encode, manipulate or eliminate the generated magnetic resonance, detect magnetic resonance, and perform other MR imaging or spectroscopy related operations Can be realized by a magnetic field gradient coil and a radio frequency subsystem.

  MR scanners generate substantial stray magnetic fields and radio frequency interference (RFI) and are generally housed in a dedicated MR room that is shielded to isolate the MR scanner from nearby electronic systems. Since magnetic materials can be attracted towards the MR scanner magnet and sometimes with catastrophic consequences, safety protocols are used to limit the possibility of such magnetic materials being brought into the MR room. ing. Under such a protocol, MR can be used safely and usefully for a variety of medical applications.

  However, some patients find MR imaging or spectroscopy a stressful procedure. The unfortunate result is that patients undergoing MR procedures may experience cardiac arrest. In principle, anyone can experience cardiac arrest at any time; in fact, cardiac arrest is substantially more likely to occur in sick people, the elderly, hospitalized patients, etc., where the person represents, for example, a serious health problem or It is more likely to occur when undergoing stressful experiences, such as when inserted into a closed or restricted bore of an MR scanner for an apparent MR procedure. In short, patients undergoing MR procedures are substantially more likely to experience cardiac arrest compared to members of the general population.

  Patients experiencing cardiac arrest can be revived using a cardiac defibrillator such as an automatic external defibrillator (AED). Immediate emergency responses, including immediate application of defibrillators, are known to be critical for successful patient resuscitation. Delays in delivering defibrillation shocks to victims of cardiac arrest are expected to reduce survival by 10 per minute. Please refer to http://aed.com/faqs/#q03 (last access July 24, 2009). In terms of this urgency, keep the defibrillator operable in “non-medical” locations such as workplaces, schools, churches, etc. so that the defibrillator can be applied immediately in case of cardiac arrest Is encouraged to do so.

  However, the defibrillator cannot be brought into the MR room because it violates the safety protocol. Instead, patients experiencing cardiac arrest during the MR procedure are withdrawn from the MR scanner bore and transferred from a couch or other MR patient support device to a wheeled stretcher for delivery, and defibrillation from the MR room to the patient. Being carried out to a location that can be safely applied to. Valuable seconds or minutes can be lost during this sequence of actions, thus greatly reducing the likelihood of successful patient resuscitation. Cardiopulmonary resuscitation (CPR) can be advantageously applied during patient delivery, but it is not possible to continuously apply CPR while delivering a patient from within an MR scanner bore to a location where defibrillation can be applied. Have difficulty. In addition, CPR generally does not resuscitate patients experiencing cardiac arrest, but merely supplies some blood flow to the brain and other vital organs, which can reduce the occurrence of tissue damage. It is known to delay. Furthermore, applying CPR to sick or elderly patients can cause bruises, rib fractures or other physical trauma. The present invention provides a new and improved apparatus and method that overcomes the above-referenced problems and others.

  In accordance with one disclosed aspect, a cardiac defibrillator provides electrical wires or terminals connected to or configured to be connected to a defibrillation electrode pad, a storage element and a cardiac defibrillation shock. An electrical circuit having a piezoelectric transformer configured to charge a storage element to a voltage effective to perform the storage element through the electrical wire or terminal to supply a cardiac defibrillation shock to the electrical wire or terminal An electrical circuit configured to discharge.

  According to another disclosed aspect, the cardiac defibrillator in the upper paragraph determines (i) a cardiac condition based on an electrocardiogram (ECG) signal received at an electrical wire or terminal, and (ii) determines A cardiac defibrillator further comprising an automatic control circuit configured to operate the electrical circuit to deliver a cardiac defibrillation shock to the electrical wire or terminal if the performed cardiac condition indicates cardiac arrest Defines an automatic external defibrillator (AED).

  According to another disclosed aspect, a cardiac defibrillator includes an electrical wire or terminal connected to or configured to be connected to a defibrillation electrode pad, a storage element and a magnetic body, An electrical circuit having a transformer configured to charge a storage element to a voltage effective to supply a defibrillation shock, wherein the electrical wire or And an electric circuit configured to discharge the storage element through the terminal.

  According to another aspect disclosed, a magnetic resonance facility includes a magnetic resonance scanner, a shielded room containing the magnetic resonance scanner, and any of the above three paragraphs disposed in the shielded room. A cardiac defibrillator as described in one of the above.

  According to another aspect disclosed, an apparatus includes an electrical wire or terminal configured to electrically communicate with the heart, and a storage element and a piezoelectric transformer configured to charge the storage element. An electrical circuit configured to discharge the storage element through an electrical wire or terminal to provide electrical stimulation to the heart.

  One advantage resides in providing a defibrillator with MR coexistence.

  Another advantage resides in reducing the delay between the occurrence of cardiac arrest in patients undergoing MR procedures and the onset of life-threatening cardiac defibrillation.

  Another advantage resides in providing an electrical device for cardiac electrical stimulation that is substantially insensitive to magnetic fields.

  Other advantages will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description.

1 schematically shows an MR facility having an MR scanner placed in a shielded room and further including a cardiac defibrillator. FIG. The figure which shows schematically the defibrillator of FIG. FIG. 3 schematically illustrates a suitable embodiment of the electrical circuit of FIG. FIG. 3 schematically illustrates a suitable embodiment of the electrical circuit of FIG.

  Referring to FIG. 1, the magnetic resonance facility includes a magnetic resonance (MR) scanner 10 disposed in a shielded room 12 (shown schematically as a dotted box in FIG. 1). The illustrated magnetic resonance scanner 10 is an Achieva MR scanner available from Koninklijke Philips Electronics N.V. (Eindhoven, The Netherlands). However, essentially any MR scanner may be used. As is known in the art, the MR scanner 10 generates a strong magnetic field in the bore B of the MR scanner 10. The magnetic field in the bore depends on the design of the MR scanner 10, but is generally in the range of about 0.1 Tesla to 7.0 Tesla or higher. Furthermore, it is expected that the stray field extends a large distance outside the bore B. MR scanner 10 is also sensitive to radio frequency interference (RFI) and can generate RFI that can interfere with other nearby electronic systems. The shielded room 12 provides an electromagnetic shield against RFI and optionally also includes a magnetic shield to prevent stray magnetic fields from passing beyond the border of the shielded room 12. A door or other entrance 14 provides access to the shielded room 12. Although only one inlet 14 is shown, multiple inlets are further contemplated. The subject to be imaged is conveyed through the inlet 14 to the MR scanner 10 and placed on the bed of the MR scanner 10 or other subject support 16. The object support 16 generally has a pallet (not shown in detail) that can be moved in parallel, and the pallet can be used for MR imaging, MR spectroscopy, or another object placed on the object support 16. It is translated into bore B for the MR procedure and allows it to be accurately positioned therein.

  Preferably, the safety protocol indicates what items are allowed in the shielded room 12. The safety protocol removes items containing magnetic material because of the possibility that the magnetic material may interact adversely with the MR scanner 10. The safety protocol is selected to undergo medical procedures, medical screening subjects, veterinary subjects, inanimate subjects such as archaeological mummy, or MR procedures using the MR scanner 10. To other subjects. General safety protocols for medical facilities are (1) interrogating the subject regarding possible surgical implants (pacemakers, orthopedic implants, etc.), (2) before entering the shielded room 12 Requiring removal of all metal from the patient, (3) a metal detector (not shown) at the inlet 14 to detect metal that can be inadvertently seen by procedures (1) and (2) ). The safety protocol described above is intended to remove not only magnetic material, but more generally any metal or other conductive material. The reason for this is that the conductive material placed in bore B may support eddy currents generated by time-varying magnetic fields, which can cause heating and possibly injure the subject. Because.

  The illustrated MR facility further includes a cardiac defibrillator 20. A cardiac defibrillator is a device configured to deliver a cardiac defibrillation shock to a patient experiencing cardiac arrest. To this end, the cardiac defibrillator 20 has a pair of electrode pads 22 that are configured to be connected to or connected to the cardiac defibrillator 20 via electrical wires or terminals 24. The electrode pad 22 is configured for electrical external contact with the barrel, and optionally has an adhesive function or other securing function (not shown) for secure attachment to the barrel. The torso is generally the human torso when a person is experiencing cardiac arrest, but the canine, feline or other torso when a veterinary subject is experiencing cardiac arrest. Is further contemplated. The number of electrode pads 22 (and hence the corresponding number of electrical wires or terminals 24) is generally 2 to allow defibrillation to be delivered across the subject's torso, eg, an electric shock Further contemplated is the use of three or more electrode pads (and corresponding electrical wires or terminals) to provide the desired pattern. The electrical wire or terminal 24 can have an electrical connector (eg, a socket or the like) to which the cable of the electrode pad 22 is detachably connected (as in the case of a modular or replaceable electrical pad), or ( It can be a conductive wire that is in electrical contact with electrode pad 22 and permanently fixed (as in the case of “hard-wired” electrode pads).

  The illustrated cardiac defibrillator 20 is an automatic external defibrillator (AED). The AED (i) determines a heart condition based on an electrical signal received at the electrical terminal 24 via the electrode pad 22 and (ii) if the determined cardiac condition indicates cardiac arrest, the heart through the electrical terminal 24 A cardiac defibrillator having an electrical circuit configured to deliver a defibrillation shock. The AED shown further has a user interface in the form of a display 26 to convey operational instructions to the user. The user interface can, for example, inform the user whether defibrillation is appropriate and, if so, can instruct the user on how to apply the defibrillation shock (eg, defibrillation). Tell the user that no one should touch the subject when the shock is delivered). Instead of or in addition to the display 26 shown, the user interface can have audio speakers or other output devices, and optionally has one or more buttons, keys or other user input devices. be able to. For example, in combination with the illustrated display 26, the AED 20 may have a button 28 that a user should press to apply a defibrillation shock. The user interface may further use a voice synthesizer to automatically convey operational instructions to the user in words.

  With continued reference to FIG. 1 and further reference to FIG. 2, cardiac defibrillator 20 has a power source, or battery 30, in the illustrative example, which provides a cardiac defibrillation shock. An electrical circuit 32 is driven that generates a valid voltage and discharges the voltage through the electrical wire or terminal 24 to deliver a cardiac defibrillation shock through the electrical wire or terminal. As disclosed herein, by configuring the electrical circuit 32 to be non-magnetic (i.e., to use non-magnetic materials and particularly non-ferromagnetic materials), the cardiac defibrillator 20 is capable of MR coexistence. Can be stored in a shielded room 12 containing the MR scanner 10. In the illustration of FIG. 1, the cardiac defibrillator 20 is placed inside the shielded room 12 so as not to get in the way, and further to provide immediate access when the patient experiences cardiac arrest. Attached to the wall. Other attachment structures are further contemplated, such as placing a cardiac defibrillator on a table.

  To achieve an automated view of the exemplary AED 20, the automatic control circuit 34 is powered by the battery 30 via a suitable power converter 36 and (i) received at an electrical wire or terminal 24. Determining a cardiac condition based on the electrical signal; and (ii) operating the electrical circuit 32 to deliver a cardiac defibrillation shock through the electrical wire or terminal 24 if the determined cardiac condition indicates cardiac arrest. Configured. Exemplary automatic control circuit 34 stores one or more memory chips, read only memory (ROM), erasable ROM (EPROM) or firmware instructions executed by a processor; analog-to-digital for reading ECG signals (A / D) embodied as a microprocessor or microcontroller with associated circuitry such as a converter, etc.

  In order to allow the electrical wire or terminal 24 to operate as both a sensor lead for determining a cardiac condition and an electrical conductor for delivering a defibrillation shock, the switches 40a, 40b, 40c, 40d are: An electrical wire or terminal 24 is selectively connected to either an electrical circuit 32 (for delivering a defibrillation shock) or an electrocardiograph (ECG) input 42 of an automatic control circuit 34.

  During operation, the automatic control circuit 34 sets the switches 40a, 40b, 40c, 40d to connect the ECG input 42 to the electrical wire or terminal 24, and determines whether the subject is in cardiac arrest. ECG is analyzed. If this analysis indicates cardiac arrest, the automatic control circuit 34 operates the electrical circuit 32 to produce a voltage effective to deliver a cardiac defibrillation shock and defibrillation should be applied. This is communicated to the user via the display 26 and optionally other instructions are provided, for example to instruct the user not to touch the subject during defibrillation. When electrical circuit 32 is charged, automatic control circuit 34 sets switches 40a, 40b, 40c, 40d to connect electrical circuit 32 to wire or terminal 24, and display 26 applies a defibrillation shock. In order to do so, the user is instructed to press the button 28. When the user presses button 28, electrical circuit 32 discharges through wire or terminal 24 to deliver a defibrillation shock to the heart through electrical wire or terminal 24 and the torso of the subject experiencing cardiac arrest. To do. After the defibrillation shock is delivered, the automatic control circuit 34 resets the switches 40a, 40b, 40c, 40d to reconnect the ECG input 42 and the electrical wires or terminals 24, and again the subject is now The ECG is analyzed to determine if it is still in cardiac arrest. If the subject is still in cardiac arrest, the automatic control circuit 34 again causes the electrical circuit 32 to generate a voltage effective to deliver a cardiac defibrillation shock and another defibrillation shock. Continue to tell the user to supply.

  The cardiac defibrillator 20 shown in FIGS. 1 and 2 is an AED. However, it is further contemplated that the cardiac defibrillator 20 is a more conventional (or alternatively less automated) device that does not provide ECG monitoring and analysis or user instructions. For example, the cardioverter defibrillator can omit the ECG, user interface components 26, 28, switches 40a, 40b, 40c, 40d, and charge effective to deliver a cardiac defibrillation shock to the electrical circuit 32. And having a simplified control circuit sufficient to discharge through the wire or terminal 24 to produce a defibrillation shock.

  Inclusion of magnetic material within the defibrillator generally makes it unsuitable for the defibrillator to enter a shielded room 12 that houses the MR scanner 10. This is due to concerns that the magnetic material can adversely interact with the magnetic field of the MR scanner 10. For example, the magnetic material may be forcibly attracted to bore B and may collide with the bore wall with a large force, thus causing damage to MR scanner 10 and / or defibrillator and / or to bore B. Occasionally, any placed subject may be injured. Furthermore, it has been found that defibrillators can fail to operate properly when stray magnetic fields are present. In fact, a magnetic field as low as about 0.1 T can cause saturation of the transformer core and thus lead to defibrillator failure. A relatively low magnetic field can cause abnormal transformer operation and impair the operation of the defibrillator. A malfunction or failure of the defibrillator used during the cardiac arrest event is undesirable.

  Thus, the cardiac defibrillator 20 contains almost no magnetic material, and preferably no magnetic material. Specifically, the electric circuit 32 does not use a conventional transformer including a ferromagnetic core. Furthermore, the air core transformer does not use an air core transformer because the air core transformer is not effective to quickly generate a voltage effective to deliver a cardiac defibrillation shock.

  With reference to FIGS. 3 and 4, two embodiments of suitable electrical circuits 32a, 32b are illustrated, both of which are used as the electrical circuit 32 of the cardiac defibrillator 20 of FIGS. Can. In both exemplary electrical circuits 32a, 32b, the piezoelectric transformer 50 is configured to charge the storage element 52, ie, the storage capacitor of the embodiment of FIG. 3, to a voltage effective to supply a cardiac defibrillation shock. Is done. The piezoelectric transformer 50 advantageously does not include a magnetic or ferromagnetic material and does not have a magnetic core that can be saturated by an ambient magnetic field. In general, a piezoelectric transformer is not attracted to or affected by a strong magnetic field. Piezoelectric transformers include ceramic materials or other materials or assemblies of materials (eg, multilayer structures) that exhibit a strong piezoelectric effect. This material or assembly of materials that exhibits a strong piezoelectric effect is referred to herein as a piezoelectric core 54. The input AC voltage is applied to the piezoelectric core 54 through the piezoelectric transformer input terminal 56. The strong piezoelectric effect of the piezoelectric core 54 converts the input AC voltage into mechanical vibration. These vibrations are converted to a higher voltage electrical output at an output terminal 58 that is further coupled to the piezoelectric core 54, which is a stepped piezoelectric transformer output. A suitable piezoelectric transformer for use as the piezoelectric transformer 50 is a multilayer Rosen piezoelectric transformer available from Noliac North America (Atlanta, Georgia, USA), available from Panasonic Corporation of North America (Secaucus, NJ, USA). Includes piezoelectric transformers designed for LCD backlighting and ceramic multilayer piezoelectric transformers available from Steiner & Martins, Inc. (Miami, Florida, USA). Other piezoelectric transformers can also be used.

  The higher voltage output of the piezoelectric transformer 50 is an alternating voltage. In order for the rectifier 60 to rectify the AC output of the piezoelectric transformer 50 and supply a DC voltage (possibly having a large ripple component) to charge the storage element 52, the piezoelectric transformer 50 and the storage element 52 Arranged between. The exemplary rectifier 60 is comprised of two high voltage diodes, although other rectifier topologies including both half-wave rectifier and full-wave rectifier topologies are further contemplated. The voltage charging unit 62 with the piezoelectric transformer 50 and the rectifier 60 can be optionally duplexed in parallel to provide a greater charging capacity, or the entire circuit 32a, 32b can be duplexed for this purpose. .

  The input AC voltage supplied to the piezoelectric transformer input terminal 56 is generated by the driver subcircuit. In the embodiment of FIG. 3, the driver subcircuit 66a uses a push-pull topology that utilizes two pull-down MOSFET transistors and two air-core (and hence non-magnetic) energy storage inductors. Other driver topologies can also be used, such as the “Class A” amplifier topology driver subcircuit 66b used in the exemplary electrical circuit 32b, which circuit has a high-side / low-side MOSFET driver. Another driver topology that is mentioned as another example but not shown is a single MOSFET driver topology that preferably uses only air-core inductors again to avoid inclusion of magnetic material in the driver.

  The input AC voltage supplied to the piezoelectric transformer input terminal 56 preferably has the resonance frequency of the piezoelectric core 54 in order to maximize the voltage conversion efficiency. For this purpose, the frequency control subcircuit 70 has a phase-locked loop (PLL) 72, a sense resistor 74, and an amplification and filtering element 76, which control the frequency supplied to the drivers 66a, 66b. , Operates to ensure that the piezoelectric transformer 50 is kept near the resonant frequency. A suitable frequency control approach filters and amplifies the primary drive waveform with a bandpass filter and produces a filtered and amplified signal from the sense resistor 74. The phases of the two input signals are compared, and the frequency of the signal to the driver circuits 66a and 66b is adjusted. This control approach works well when the voltage and current are in phase because the piezoelectric element 50 is driven at its resonant frequency.

  For completeness, each of FIGS. 3 and 4 schematically illustrates a portion 84 of the automatic control circuit 34 having a charge control subcircuit 86 and a voltage scaling subcircuit 88. The charging control subcircuit 86 operates to activate the charging of the power storage element 52 by locking the frequency control subcircuit 70 to the resonance frequency of the piezoelectric transformer 50. Other approaches to turn charging on or off are further contemplated. The voltage scaling subcircuit 88 is arranged in parallel at both ends of the storage element 52 in order to control the magnitude of the voltage with which the storage element 52 is charged. For defibrillation, this voltage should be effective to deliver a cardiac defibrillation shock, and in some embodiments this voltage is in the 1500-5000 volt DC range, but more Higher or lower voltages are further contemplated.

  Referring again to FIG. 1, a cardiac defibrillator 20 is described with respect to an exemplary MR facility. However, it will be appreciated that the cardiac defibrillator 20 is useful in any device in which the cardiac defibrillator 20 encounters a substantial magnetic field. Further, although an external cardiac defibrillator is illustrated, it should be understood that the cardiac defibrillator may be an implanted defibrillator. Further, the disclosed device advantageously uses an electrical circuit having a storage element configured such that such a device is charged and discharged through an electrical wire or terminal to provide electrical stimulation to the heart. As much as possible, it is contemplated for use in implantable electronic devices that electrically stimulate the heart, such as other external electronic devices or cardiac pacemakers.

  For example, in the case of an implantable cardiac pacemaker (not shown), electrical wires or terminals (through electrode pads 22 that are in electrical contact with the torso to deliver a cardiac defibrillation shock to the heart through the torso). Properly in close contact with the heart (rather than touching), the voltage scaling sub-circuit stores power to deliver low voltage electrical stimulation to the heart to provide a cardiac pacemaker effect rather than defibrillation Appropriately configured to control the magnitude of the voltage at which the device is charged. Such implantable cardiac pacemakers are substantially insensitive to magnetic fields and are therefore MR compatible, and the person in which the device is implanted is in the vicinity of arc welding, high voltage power generation or transmission equipment. Allows you to engage in other activities that may require magnetic interaction, such as working in

  This application describes one or more preferred embodiments. Variations and modifications may occur to those skilled in the art upon reading and understanding the preceding detailed description. The present invention is intended to be construed as including all such variations and modifications as long as such variations and modifications are within the scope of the appended claims or their equivalents.

Claims (20)

An electrical wire or terminal connected to or configured to be connected to a defibrillation electrode pad;
An electrical circuit having a piezoelectric transformer that charges the electrical storage element to a voltage effective to supply an electrical storage element and a cardiac defibrillation shock, wherein the electrical circuit or the terminal is used to supply the cardiac defibrillation shock. An electrical circuit for discharging the storage element through an electrical wire or terminal;
A cardiac defibrillator.   The cardiac defibrillator according to claim 1, wherein the storage element has a storage capacitor.   3. An electrode pad connected to or configured to be connected to the electrical wire or terminal, wherein the electrode pad is in electrical contact with the torso to deliver a cardiac defibrillation shock to the torso. A cardiac defibrillator as described in.   (I) determining a cardiac condition based on an electrocardiogram signal received at the electrical wire or terminal; and (ii) a cardiac defibrillation shock applied to the electrical wire or terminal when the determined cardiac condition indicates cardiac arrest. 4. A cardiac defibrillator according to any one of claims 1 to 3, further comprising an automatic control circuit that operates the electrical circuit to deliver a signal.   The cardiac defibrillator of claim 4, further comprising a user interface for the cardiac defibrillator to communicate operational instructions to a user.   The cardiac defibrillator according to any one of claims 1 to 5, wherein the cardiac defibrillator does not include a magnetic material.   The cardiac defibrillator according to any one of claims 1 to 6, wherein the cardiac defibrillator does not include a ferromagnetic material.   The cardiac defibrillator according to any one of claims 1 to 7, wherein the electrical circuit includes a plurality of piezoelectric transformers that charge the storage element to a voltage effective to supply a cardiac defibrillation shock. . The electrical circuit includes a driver circuit that drives the piezoelectric transformer;
A frequency control sub-circuit having a phase-locked loop configured to hold the piezoelectric transformer at a resonant frequency by controlling the driver circuit;
9. The cardiac defibrillator according to any one of claims 1 to 8, wherein:   The cardiac defibrillator according to any one of claims 1 to 9, wherein the electrical circuit includes a phase-locked loop configured to hold the piezoelectric transformer at a resonant frequency.   The cardiac defibrillator according to claim 1, wherein the electric circuit includes a rectifier that is electrically arranged between an output of the piezoelectric transformer and the power storage element. An electrical wire or terminal connected to or configured to be connected to a defibrillation electrode pad;
An electric circuit that does not include a power storage element and a magnetic body and has a transformer that charges the power storage element to a voltage that is effective for supplying a heart defibrillation shock. An electrical circuit for discharging the storage element through the electrical wire or terminal for supply;
A cardiac defibrillator having   The cardiac defibrillator according to claim 12, wherein the storage element has a storage capacitor.   An electrode pad connected to or configured to be connected to the electrical wire or terminal, wherein the electrode is configured to be in electrical contact with the torso to deliver a cardiac defibrillation shock to the torso The cardiac defibrillator according to claim 12 or 13, further comprising a pad.   (I) determining a cardiac condition based on an electrocardiogram signal received at the electrical wire or terminal; and (ii) a cardiac defibrillation shock applied to the electrical wire or terminal when the determined cardiac condition indicates cardiac arrest. 15. The heart according to any one of claims 12 to 14, further comprising an automatic control circuit for operating the electrical circuit to supply an electrical defibrillator, wherein the cardiac defibrillator defines an automatic external defibrillator. Defibrillator.   16. The transformer according to any one of claims 12 to 15, wherein the transformer of the electrical circuit has one or more piezoelectric transformers that charge the storage element to a voltage effective to supply a cardiac defibrillation shock. Heart defibrillator.   The cardiac defibrillator according to claim 16, wherein the electrical circuit includes a rectifier that is electrically disposed between an output of the piezoelectric transformer and the storage element. A magnetic resonance scanner;
A shielded room containing the magnetic resonance scanner;
The cardiac defibrillator according to any one of claims 1 to 17, disposed in the shielded room;
Having magnetic resonance equipment. An electrical wire or terminal in electrical communication with the heart;
An electrical circuit having a storage element and a piezoelectric transformer for charging the storage element, the electrical circuit discharging the storage element through the electrical wire or terminal to supply electrical stimulation to the heart;
Having a device.   21. The apparatus of claim 19, wherein the electrical wire or terminal is in electrical communication with the heart through an external connection with a torso that includes the heart.

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